An anaglyph system, a passive system, an active system, and the like are known as a stereoscopic image projection system using glasses. An anaglyph system has extremely low display quality and causes crosstalk. Both a passive system and an active system use polarizing glasses.
A passive system allows lightweight polarizing glasses to be manufactured at low cost, but needs different pixels to be used to generate an image for left eye and an image for right eye. For this reason, 3D vision display needs spatial resolution twice as high as that of usual two-dimensional vision display. Therefore, stereoscopic vision generally has lower resolution. The display quality thereof is also lower than that of an active system. Further, the stereoscopic vision display needs a polarizing element such as a λ/2 plate to be patterned in each pixel, which results in an increase in the cost of the display device.
An active system has excellent display performance. For example, if the spatial resolution of a video display device (hereinafter, also referred to as “3D display device”) for a stereoscopic image projection system is full high-definition of 1920×1080, stereoscopic display is possible with full HD resolution as is. Further, the principal performance required for an active system 3D display device is a high frame rate and high image processing capacity, and current high-end video display devices can also satisfy these requirements. That is, the active system 3D display device can be offered as a 3D display device even in a stage prior to popularization of 3D contents without introducing a special member to the video display device.
Hereinafter, polarizing glasses used in an active system are also referred to as “active shutter glasses”.
As a stereoscopic image projection system employing an active system, for example, a technology using active shutter glasses having a pair of polarizers and liquid crystals disposed between the pair of polarizers is disclosed (e.g., see Patent Literature 1).
In recent years, liquid crystal display devices have been put to practical use as video display devices having features of a thin profile, a light weight, and low power consumption, and they have been widely used in various fields.
In liquid crystal display devices, technique for improving the visibility through polarizing sunglasses is disclosed.
For example, Patent Literature 2 discloses a liquid crystal display device including a liquid crystal display panel, a first polarizer, a second polarizer, and a half-wave plate. The liquid crystal display panel includes two substrates and liquid crystals disposed between the substrates. The polarizer (e.g. upper polarizer) is disposed on a side of one of the two polarizers which is opposite to the side that faces the liquid crystals of the liquid crystal display panel. The half-wave plate is disposed on the polarizer. The direction of a fast axis of the half-wave plate is set such that a polarization direction of light coming from a transmission axis of the polarizer is rotated by the range of 90±15 [°].